Golf Course Management

MAR 2018

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68 GOLF COURSE MANAGEMENT 03.18 Treatments in both studies were applied every 14 days from May to August 2010 and from May to September 2011. Applications were made using a hand-held CO 2 -pressurized sprayer with a single AI9508E flat-fan nozzle calibrated to deliver 2 gallons/1,000 square feet at 40 psi (82 milliliters/square meter at 275 kilopascals). Granular formulations were applied by hand with a shaker jar, and lightly watered in. Data collection and statistical analyses Algae infestation was assessed visually as the percent plot area blackened by algae. Data from individual dates were used to calculate the area under the algae development curve (AUADC), which reduces numerous observation dates to a single value representing the overall annual effect of each treatment. Turf quality was also visually assessed in Study 2 during July of each year using a scale of 1 to 9, where 9 represented the best quality and 6 was the minimum ac - ceptable level. Algae infestation data from Study 1 were analyzed using pre-planned statistical treat - ment comparisons (that is, contrasts). These Study 1: P os ite sources and conventional fungicides All treatments except analytical-grade po - tassium phosphate reduced algae compared with the non-treated control (Table 2, Figure 2). Analytical-grade potassium phosphite provided equivalent algae suppression compared with commercial phosphite fungicides and phos - phite fertilizers during 2010 and 2011. Algae (AUADC) was reduced 52% to 100% and 57% to 97% in plots treated with potassium phosphite compared with potassium phosphate and non-treated control plots throughout the study. Among commercial phosphite products evaluated, fungicides and fertilizers provided similar algae control in 2010 (Table 2, Figure 2). However, phosphite fertilizer-treated plots contained 5% more algae on one observation date (data not shown), increasing the AUADC compared with phosphite fungicides in 2011 (Table 2). Comparisons of various phosphite sources (for example, potassium phosphite, am - monium-potassium phosphite, sodium-ammo- nium-potassium phosphite), within phosphite fungicides and phosphite fertilizers indicated no significant differences existed among these statistical comparisons were specifically de - signed to identify all potential differences be- tween and within the various phosphonate and fungicide treatment groups evaluated. In Study 2, AUADC and turf quality data were analyzed by orthogonal contrasts to identify significant main effects and interactions. Results Algae first appeared throughout the study as areas of turf containing black aggregations of filamentous cyanobacteria (P ormidium spe - cies) in the lower canopy on June 14, 2010 and Aug. 24, 2011. Infestation of non-treated con - trol plots continued throughout July 2010, with a rapid increase occurring July 14 through 29. Algae increased to its maximum (25% of plot area infested in non-treated plots) by July 29, 2010, and remained at a similar level through - out the remainder of the study in mid-August. In 2011, algae were first observed on Aug. 24 with 19% of plot area infested in non-treated control plots. Thereafter, algae increased to 38% plot area infested in non-treated control plots by Sept. 12. Study 1: Phosphite fungicides and fertilizers and contact fungicides Application rate Trade name Product type † Active ingredient Phosphite source Formulation rate/1,000 square feet pounds a.i./1,000 square feet Manufacturer Not applicable phosphite standard phosphorous acid potassium phosphite 70.5 grams/liter 30.9 fluid ounces 0.17 Acros Organics Not applicable phosphate standard phosphoric acid potassium phosphate 85.2 grams/liter 30.9 fluid ounces 0.17 Fisher Scientific Alude phosphite fungicide phosphorous acid potassium phosphite 3.4 pounds/gallon 7.4 fluid ounces 0.20 Cleary Chemical Vital phosphite fungicide phosphorous acid potassium phosphite 4.2 pounds/gallon 5.0 fluid ounces 0.16 Phoenix Environmental Magellan phosphite fungicide phosphorous acid sodium-ammonium- potassium phosphite 4.3 pounds/gallon 4.1 fluid ounces 0.14 Nufarm Phosphite 30 phosphite fertilizer phosphorous acid potassium phosphite 0-0-27 4.0 fluid ounces 0.14 Plant Food Co. Magnum phosphite fertilizer phosphorous acid ammonium-potassium phosphite 2-0-16 1.8 fluid ounces 0.7 Verdesian Fairphyte phosphite fertilizer phosphorous acid potassium phosphite 1-0-26 4.5 fluid ounces 0.9 Grigg Daconil Ultrex fungicide chlorothalonil not applicable 82.5WDG 3.4 ounces 0.18 Syngenta Protect fungicide mancozeb not applicable 75DF 6.0 ounces 0.28 Cleary Chemical TerraCyte fungicide sodium carbonate peroxyhydrate not applicable 34G 8.0 pounds 3.0 pounds 2.72 ‡ 1.02 BioSafe Systems † All treatments except sodium carbonate peroxyhydrate were applied at a volume of 2 gallons/1,000 square feet via a single AI95008E nozzle every 14 days from May 20 to Aug. 26, 2010, and from May 25 to Sept. 30, 2011. ‡ Sodium carbonate peroxyhydrate was applied with a hand-held shaker jar, initially at 8 pounds/1,000 square feet, on May 20, 2010 and May 25, 2011, and at 8 pounds/1,000 square feet every 14 days thereafter. Table 1. Phosphite fungicides, phosphite fertilizers and contact fungicides evaluated in Study 1 for cyanobacteria control in creeping bentgrass putting green turf in Storrs, Conn., during 2010 and 2011.

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